With the quick development in the wireless communication technological fields, more attention has been drawn to the requirements for signal transmission quality, compactness and low weight of all kinds of electronic communication devices. Generally, antennas for various kinds of mobile video communication products, such as tablet computers and cellular phones, have differently designed main body structures and circuit arrangements corresponding to the appearances and internal structures of the products, in order to satisfy the requirement for miniaturized communication devices.
According to a currently available forming technique, namely, laser direct structuring (LDS), a specific and laser-activatable plastic material can be injection-molded into a predetermined main body structure, and a laser beam with a specific wavelength is used to activate metal crystal grains doped in the plastic material while simultaneously defining a circuit pattern on the main body. Finally, a metallization process is performed on the main body to obtain a desired circuit. The technique of LDS is frequently applied to different products, including, but not limited to, cellular phones, antennas for mobile computers, light-emitting diode (LED) modules, in-car devices and the like.
However, the plastic material for use with LDS must be doped with a metal catalyst, and the ratio of different components of the doped metal catalyst must be changed according to the type and the material property of the plastic material used. Further, the conditions for laser activation vary with different doped metal catalysts. Therefore, in using the technique of LDS, it is necessary to adjust laser wavelength and control parameters for subsequent metallization process according to the plastic material used and the doped metal catalyst. That is, the LDS technique requires laser equipment that can provide laser beams of specific wavelengths as well as metallization equipment that can be set to different conditions or control parameters, and therefore, requires rather expensive equipment and manufacturing costs.
Moreover, in using the LDS technique, rising of main body surface temperature would cause removal or breakdown of metal crystal grains on part of the main body surfaces or even cause deposition of metal crystal grains on the main body surfaces at areas not expected for forming the circuit, resulting in reduced selectivity of deposited conducting circuit in the subsequent metallization process and accordingly, the problem of short-circuiting between adjacent electronic elements. To prevent any possible short circuit and any possible problem in the subsequent metallization process, it is necessary to control the space between circuit paths during LDS.
However, large space between circuit paths would often cause another problem of insufficient circuit density. It is therefore tried by the inventor to develop a method of manufacturing plastic metallized three-dimensional (3D) circuit to overcome the problems and drawbacks in the conventional techniques for forming circuits on miniaturized electronic devices.